Make MCP writes retry-safe and coordination state visible to agents

- Send Idempotency-Key on node create/patch/update writes (including bulk,
  link, move, kanban and agent-node tools) and return the key used, so an
  ambiguous failure can be retried without duplicating the write.
- Record a non-secret marker when login renewal is rejected; nap_whoami
  reports auth_required ahead of gateway state, and local-index answers
  carry stale warnings instead of silently serving old memory.
- Add nap_kanban_claim_next: pick and claim in one call, skipping cards
  held by another operation, never replaying an ambiguous claim.
- Add nap_changes_since over /v1/projects/{id}/changes with a
  per-worktree cursor that only advances after a successful read.
- Report real links_count/backlinks_count from indexed edges.
- Accept optional tool_profiles in .napseer/project.json when
  NAPSEER_TOOL_PROFILES is unset.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/test_mcp_memory_ergonomics_helpers.py

@@ -283,7 +283,7 @@ def test_node_get_rejects_path_reads(mod):
 
 def test_tools_include_node_by_path_descriptor(mod):
     tool_by_name = {item["name"]: item for item in mod.tools()}
-    assert len(tool_by_name) == 58
+    assert len(tool_by_name) == 60
     assert len(tool_by_name) == len(mod.tools())
 
     get_tool = next(item for item in mod.tools() if item["name"] == "nap_node_get")